APPLICATION OF ADDITIVE TECHNOLOGY OF FUSED DEPOSITION MODELING FOR MANUFACTURING SMALL SERIES OF ELASTIC MODELS

The paper presents an application of additive method of Fused Deposition Modeling for manufacturing of small series of elastic models. Additive FDM technology is used to produce a casting mould for multiple use. Process of manufacturing of small series of products consists in casting a two-component silicone rubber degassed using vacuum chamber into a multiple use mould. The paper shows the course of the process and related problems on the example of industrial product – a cylindrical seal. The casting mould was produced out of ABS material using BST 1200 machine, whereas casted elastic models were made out of XTX 45 silicone rubber

Manufacturing of thin-walled, complex polymer parts by DLP printing – the influence of process parameters on crosslinking density

This study investigated the relationship between the parameters of the DLP manufacturing process and the structure of photopolymerizable acrylic resins. Four different process parameters were established to produce different thin-walled acrylic sample series: exposure time, layer thickness, area offset, and number of transition layers. The structure and the surface of the obtained samples were examined with the use of the FTIR–ATR method and an optical microscope, respectively. It was proved that extension of the exposure time increases the density of crosslinking and sample thickness. A decreasing crosslinking density due to rising layer thickness is observed. The area offset affects only the dimensions of the sample, predictably reducing the dimensions of the sample as the compensation increases. The absence of transition layers proved unfavorable in many respects, both structurally and geometrically

The Bcl I single nucleotide polymorphism of the human glucocorticoid receptor gene h-GR/NR3C1 promoter in patients with bronchial asthma: pilot study

Bcl I in the promoter polymorphism observed within h-GR/NR3C1 gene may play an important role in the development of bronchial asthma and resistance to GCs in the severe bronchial asthma. The aim of the investigation was to study the correlation between this h-GR/NR3C1 gene polymorphism and occurrence of asthma in the population of Polish asthmatics. Peripheral blood was obtained from 70 healthy volunteers and 59 asthma patients. Structuralized anamnesis, spirometry and allergy skin prick tests were performed in all participants. Genotyping was carried out with PCR–RFLP method. In healthy, non-atopic population variants of Bcl I: GG, GC, CC were found with frequency 0.129/0.471/0.400, respectively. In asthma patients Bcl I: GG, GC, CC occurred with respective frequencies of 0.410/0.462/0.128. Chi-square analysis revealed a significantly different (P < 0.05) distribution between cases and controls for the Bcl I polymorphism. The Bcl I polymorphism of h-GR/NR3C1 gene is significantly associated with bronchial asthma, susceptibility to the development of severe form and resistance to GCs in Polish population

ELASTIC PROPERTIES OF COMPOSITES REINFORCED BY WAVY CARBON NANOTUBES

In the paper the prediction of the elastic Young modulus of single-walled carbon nanotubes (CNTs) and the elastic properties of composites reinforced by straight or wavy CNTs is presented. The properties are evaluated by numerical methods. Nanotubes are modeled and analyzed by the finite element method (FEM). The specific atomistic nature of CNTs is taken into account by using a linkage between molecular and continuum mechanics. The methodology consists in replacing the discrete molecular structure of a CNT with a space-frame FE model by equating the molecular potential energy and the elastic strain energy of both models subjected to small elastic deformations. A three-dimensional frame is further substituted with a one-dimensional beam which represents the reinforcement in a representative volume element (RVE) of the considered composite. The properties of the nano-composite are determined by modeling and analyzing RVEs using the coupled boundary and finite element method (BEM/FEM). A two-dimensional matrix is modeled by the BEM and CNTs by the FEM using beam elements. The waviness and shape of a single fiber or multiple aligned nanotubes on the properties of the nanocomposite are investigated. Sinusoidal or arbitrary shapes of the reinforcement are considered. The influence of volume fraction of the reinforcement and the fiber/matrix Young's modulus ratio on the elastic properties of the composite is also studied

Elastic properties of composites reinforced by wavy carbon nanotubes Własności sprężyste kompozytów wzmacnianych krzywoliniowymi nanorurkami węglowymi /

Tyt. z nagłówka.Bibliogr. s. 211-[212].Artykuł dotyczy wyznaczania modułu Younga jednościennych nanorurek węglowych oraz własności sprężystych kompozytów wzmacnianych prostymi nanorurkami lub o dowolnym kształcie. Własności są wyznaczone metodami numerycznymi. Nanorurki modelowane i analizowane są metodą elementów skończonych (MES). By uwzględnić specyficzną budowę atomową nanorurek, zastosowano połączenie mechaniki molekularnej i kontynualnej. Metoda polega na zastąpieniu dyskretnej struktury nanorurki przez model MES w postaci ramy przestrzennej przez porównanie potencjalnej energii molekularnej i sprężystej energii odkształcenia obu modeli, podlegających małym odkształceniom sprężystym. Trójwymiarowy model ramy jest następnie zastąpiony jednowymiarową belką, która reprezentuje wzmocnienie w reprezentatywnym elemencie objętościowym (RVE) rozważanego kompozytu. Własności nanokompozytu wyznacza się, modelując i analizując RVE połączoną metodą elementów brzegowych i skończonych (MEB/MES). Osnowa modelowana jest MEB jako ciało dwuwymiarowe, natomiast nanorurki MES za pomocą elementów belkowych. Badano wpływ falistości oraz kształtu pojedynczych lub wielu podobnie zorientowanych nanorurek na własności kompozytu. Rozważano sinusoidalne lub dowolne kształty wzmocnienia. Badano także wpływ udziału objętościowego wzmocnienia oraz stosunku modułów Younga osnowy i nanorurek na własności sprężyste kompozytu.In the paper the prediction of the elastic Young modulus of single-walled carbon nanotubes (CNTs) and the elastic properties of composites reinforced by straight or wavy CNTs is presented. The properties are evaluated by numerical methods. Nanotubes are modeled and analyzed by the finite element method (FEM). The specific atomistic nature of CNTs is taken into account by using a linkage between molecular and continuum mechanics. The methodology consists in replacing the discrete molecular structure of a CNT with a space-frame FE model by equating the molecular potential energy and the elastic strain energy of both models subjected to small elastic deformations. A three-dimensional frame is further substituted with a one-dimensional beam which represents the reinforcement in a representative volume element (RVE) of the considered composite. The properties of the nano-composite are determined by modeling and analyzing RVEs using the coupled boundary and finite element method (BEM/FEM). A two-dimensional matrix is modeled by the BEM and CNTs by the FEM using beam elements. The waviness and shape of a single fiber or multiple aligned nanotubes on the properties of the nanocomposite are investigated. Sinusoidal or arbitrary shapes of the reinforcement are considered. The influence of volume fraction of the reinforcement and the fiber/matrix Young's modulus ratio on the elastic properties of the composite is also studied.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: nanorurki węglowe, nanokompozyty, własności sprężyste, metoda elementów brzegowych, metoda elementów skończonych. KEYWORDS: carbon nanotubes, nanocomposites, elastic properties, boundary element method, finite element method

Criminal Medical Experiments on the Skeletal System of the Lower Limbs Conducted on Polish Women – the Prisoners of Ravensbrück Concentration Camp and Their Consequences for the Quality of Life, Health and Later Functioning of the Patients Operated

Artykuł interdycyplinarnie przedstawia eksperymenty prowadzone przez niemieckich lekarzy w KL Ravensbrück na Polkach i ich wpływ na losy operowanych. Omówiono eksperymenty na kończynach dolnych: czyste kostne i septyczno-kostne. W oparciu o materiał dowodowy, ekspertyzy lekarskie i wspomnienia operowanych przedstawiono przebieg operacji i ich następstwa. Po wojnie eksperymenty te uznano za zbrodnie wojenne i przeciwko ludzkości. W zależności od stopnia okaleczenia podczas operacji oraz braku opieki pooperacyjnej i rehabilitacji, stresu wojennego, złych warunków obozowych u operowanych wystąpiło pogorszenie stanu zdrowia. Autorzy uznali doświadczenia za zbrodnicze eksperymenty medyczne. Dokonywali ich lekarze, ale z pogwałceniem etyki lekarskiej. Przeprowadzano je na zdrowych kobietach. Na skutek doświadczeń dochodziło do upośledzenia sprawności fizycznej, co prowadziło nawet do kalectwa. Ponadto wystąpił silny zespół stresu pourazowego, na który nałożyła się trauma poboozowa i krzywda związana z eksperymentami. Z racji dolegliwości chorobowych część kobiet została wyłączona z ról społecznych

Determination of the Elasticity Modulus of Additively Manufactured Wrist Hand Orthoses

The article describes the experimental and simulation research on the material properties of the individualized wrist orthoses produced in the additive manufacturing (AM) process by the fused filament fabrication (FFF) method. The authors produced a series of standard (normalized) samples for three-point bending from acrylonitrile butadiene styrene (ABS) filament on a low-budget 3D printer and a series of samples in the shape of a fragment of the orthosis and the entire orthosis. All types of samples were subjected to experimental tests on a universal testing machine, which allowed us to determine the modulus of elasticity of the produced materials by comparing it with finite element method (FEM) simulation models in the ABAQUS environment. The adopted research methodology allowed us to compare the material properties of the material of the entire product&mdash;wrist hand orthosis (WHO)&mdash;with the material properties of standard bending samples. The obtained values of Young&rsquo;s modulus are characterized by a large discrepancy between the standard samples and the entire orthosis. On the other hand, the samples with the shape of the middle part of the orthosis were similar in the value of Young&rsquo;s modulus to the results obtained during the examination of the complete orthosis

INFLUENCE OF PROCESS PARAMETERS ON DIMENSIONAL ACCURACY OF PARTS MANUFACTURED USING FUSED DEPOSITION MODELLING TECHNOLOGY

The paper presents the results of experimental study – part of research of additive technology using thermoplastics as a build material, namely Fused Deposition Modelling (FDM). Aim of the study was to identify the relation between basic parameter of the FDM process – model orientation during manufacturing – and a dimensional accuracy and repeatability of obtained products. A set of samples was prepared – they were manufactured with variable process parameters and they were measured using 3D scanner. Significant differences in accuracy of products of the same geometry, but manufactured with different set of process parameters were observed

Prototyping of Cosmetic Prosthesis of Upper Limb Using Additive Manufacturing Technologies

This paper describes prototyping of an individualized cosmetic arm prosthesis. Aim of the studies was to obtain an anatomically correct, lightweight prosthesis. It was accomplished using additive manufacturing technology of fused deposition modeling. The data was obtained by 3D scanning. An experimental concept of dual extrusion of two different materials was applied – the prosthesis was divided into an elastic shell and a rigid core, manufactured in one process. Obtained results were positive

Methodology of Low Cost Rapid Manufacturing of Anatomical Models with Material Imitation of Soft Tissues

The pre-operative preparation of a surgeon is increasingly often extended to individual patient’s anatomical models depicting the affected organ and the existing lesion in relation to the surrounding structures (e.g. blood vessels). Among the models, there are models of the skeletal system, in which the FFF technology is used. The models of parenchymal organs are more difficult to reproduce due to the material limitations in the FFF technology, which is why alternative technologies such as PolyJet and SLA are used. Due to the high price of models, they are employed less frequently, especially in the Polish hospitals. The research presented in the article deals with the modification of the existing methodology of rapid pre-operative models production with the use of various low-budget rapid manufacturing techniques, which use materials of low hardness, similar to the human soft tissues. The aim was to create a methodology and determine the parameters of materials that allow for the cheap production of functional pre-operational aids